Stacking rings



FIG. 1 is a perspective view of stacking rings showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is an enlarged view of portion 8 shown in FIG. 1 ; and,

FIG. 9 is an enlarged view of portion 9 shown in FIG. 1 .

The broken lines depict portions of the stacking rings that form no part of the claimed design. 

CLAIM The ornamental design for stacking rings, as shown and described. 